1. Field of the Invention
The present invention relates to automatic creation of a test table in a monitoring control system.
2. Description of the Related Art
A monitoring control system is a system for providing an operating/monitoring person with a temperature, a pressure, a position and other information items from devices to be monitored such as various kinds of sensors and for controlling various kinds of devices such as a motor, a valve, a switch, and a hydraulic device through the operation of the operating/monitoring person; it is utilized in many fields such as a power generation plant, a chemical plant, an electricity reception/distribution system, and a water supply and sewerage system.
A typical monitoring control system has a configuration as illustrated in FIG. 2. The monitoring control system is configured with a module that performs signal transmission and reception with a device to be monitored, a module that performs information exchange with an operating/monitoring person, a module that performs calculation based on those information items, and the like; these modules are connected with one another through communication paths.
In general, the processing contents of each module in the monitoring control system are expressed by directed graphs as is the case with a circuit diagram. Signal processing is expressed by a node, and the flow of a signal is expressed by a link that connects nodes. Hereinafter, a node where signal processing is performed is referred to as an arithmetic element, and a link that connects arithmetic elements is referred to as a signal line. The processing contents of a module were achieved by a hardware circuit in the past; however, in recent years, in view of flexibility and cost performance, processing is mostly achieved by simulating the operation by use of a digital computer, i.e., processing is implemented as a program of the digital computer.
Standards of programming languages for expressing processing contents by arithmetic elements and signal lines are typified by the international standard IEC61131-3. Arithmetic elements are described by a FBD (Function Block Diagram) of the international standard; for example, it is expressed as illustrated in FIG. 4. Processing contents expressed by arithmetic elements and signal lines are represented, for example, as in FIG. 3. In the present invention, a drawing configured with signal lines and arithmetic elements for processing the signal lines is referred to as a logic drawing, hereinafter.
In recent years, as the scale of a program has become larger, it has been becoming difficult to appropriately extract test items of a program. To date, as far as logic drawings are concerned, there has been no method of efficiently extracting test items; therefore, it has relied on designers' experiences and the like. In addition, in order to actually perform a test, it has been required that not only test items but also specifically inputted values, the desirable values (expected values) outputted in response to the input, and the like are written so that a test table is created.
Patent Document 1 discloses an example where test items of a program are extracted. A program test specification creation system disclosed in Patent Document 1 is a system for analyzing a program and extracting test items in accordance with the importance so as to create a program test specification. There are provided a program analysis unit that extracts variables and functions from a program, a display unit that displays the extracted variables and functions, an input unit for inputting information that specifies a variable and a function, a test item extraction unit that extracts a description including the variable and the function specified by the inputted information, and a specification creation unit that creates a program test with the extracted description utilized as a test item. In addition, there is provided a mechanism in which variables and functions are selected based on an occurrence rate or the number of steps (nest level) of a control structure and then a specification is created for the variables and the functions through the same procedure.